In English, tonne is the established spelling. It is usually pronounced the same as ton , but the final "e" can also be pronounced, i.e. "tunnie". In Australia, it is also pronounced ton. In the United States, metric ton is the name for this unit used and recommended by NIST; an unqualified mention of a ton almost invariably refers to a short ton of 2,000 pounds (907 kg), and tonne is rarely used in speech or writing. Both terms are acceptable in Canadian usage.

Ton and tonne are both derived from a Germanic word in general use in the North Sea area since the Middle Ages to designate a large cask, or tun. A full tun, standing about a metre high, could easily weigh a tonne.